This invention relates to a method for assembling a postal item using a system comprising a first delivery station, at least one next delivery station and a folding station, in which documents are delivered by these delivery stations, which documents are transported and are gathered into a stack having on one side substantially aligned document edges, which stack is supplied to the folding station in a direction transverse to these edges.
As used herein, a "delivery station" is any station capable of delivering documents intended for a postal item to be mailed, e.g. a printer, a burster, a feeder station or a cross folding machine for longitudinally folding a document.
A method as described above is known from U.S. Pat. No. 3,260,517.
In this known method a main document is carried by transport means along a plurality of delivery stations, one or more of which delivery stations can deliver at least one secondary document. The secondary document is added to the main document when it passes the relevant delivery station. A secondary document may be, e.g., a general enclosure or a unique document belonging to the given main document.
It is a drawback of these known methods that a document to be added to the main document is to be delivered in such a manner that one of its edges is positioned in closely aligned condition--i.e. located in the same plane in the direction of the stack--relative to the corresponding edge of the main document. This demands a lot of the transport means and the delivery stations. Moreover, it must be ensured that during transport and when adding further secondary documents the resulting alignment is not lost.
In order to obtain an acceptable result when folding and to ensure that the folded stack of documents fits into the corresponding envelope, in practice, when supplying the stack to the folding station, a misalignment between the aligned edges of two stacked documents of not more than 5 mm is acceptable and of less than 2 mm is desirable.
Delivery stations which meet the above requirements are relatively expensive and complicated and also cover a relatively large space. In particular owing to its great length a system comprising such delivery stations constitutes an obstacle in a workroom in which it can hardly be accommodated.
For assembling very large amounts of postal items it is known to fold each document to be folded individually prior to delivering it, owing to which the accuracy with which the enclosure documents are added only needs to meet relatively low requirements. If required, these documents may shift in the envelope relative to each other. Such a method is described in German patent application 29 40 771.
It is a drawback of this method that machines adapted to deliver folded documents from a plurality of delivery stations are expensive because for each delivery station for delivering documents to be folded a corresponding folding station is required. It is a further drawback of this known method that folded documents are hard to control when being delivered and transported further because they tend to fold open again in various measure.